Olefin compounds, such as ethylene, propylene, butylene and amylene, can be formed from pyrolytic cracking of light petrochemicals. During the cracking process, secondary reactions may also occur producing aldehydes. As a result, the cracked hydrocarbon product stream can also contain significant quantities of aldehydes.
The cracked hydrocarbon product stream is cooled to remove most of the heavier hydrocarbons and is then compressed. When the cracked hydrocarbon stream is passed through a basic wash to remove acidic compounds, such as carbon dioxide and hydrogen sulfide, the aldehydes will undergo polymerization to form condensation polymers known as aldol polymers or red oil. Aldol polymers are essentially insoluble in the alkaline wash and the hydrocarbon media and can deposit on the internal surfaces of process equipment. These deposits can restrict flow through the equipment, which causes the pressure drop to increase across the treating vessel, resulting in a loss of capacity and increased operating costs. If left untreated, the deposition from the fouling components can result in the premature shutdown of a cracking operation.
Many of the additives available for treating petrochemical processes for removing aldehydes are not environmentally friendly. For example, additives containing nitrogen can contaminate wastewater streams requiring treatment before discharge.
What is needed is an effective and environmentally friendly treatment for reducing fouling and minimizing the deposition of fouling compounds during the basic wash stage of petrochemicals processing.